GD7
The subduction factory; inputs, outputs and mantle recycling
Subduction zones are the locus of mass
and energy transfer between the underthusting and overriding plates
as well as of lithospheric recycling into the mantle. As ocean
plates approach subduction zones they bend, fault, change their
chemistry and loose heat by poorly understood processes. Along
the first tens of km of the subduction zone, sediment compaction
and metamorphic reactions in the upper section of the slab contribute
to the return of fluids to the oceans and may control the mechanical
coupling leading to interplate thrust earthquakes. Mass transfer
between subducting and overriding plates may form accretionary
prisms or produce tectonic erosion by removal of material of the
upper plate. The rates of accretion and erosion and the nature
of the material involved are key to quantify the input into the
subduction system, but are poorly known for most convergent margins.
Deeper into the subduction zone, at depths between ~ 50 to 200
km, mechanical coupling and heat transfer between the slab and
overlying mantle lead to mantle-wedge convection. Fluids are released
from the downgoing plate and induce partial melting of the mantle-wedge
leading to arc and back-arc magmatism.
This session aims at gathering a multidisciplinary
set of presentations of scientists working in different disciplines
related to the study of the Subduction Factory. We encourage submission
of abstracts presenting data and models based on geological, geophysical,
geochemical, experimental and numerical methods.
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GD8 Dynamics and Thermal
Structure of Subduction Zones
Modeling has become an essential complementary
approach to observational and experimental ones, but major obstacles
still exist on the road to full integration of accurate and consistent
modeling into subduction zone research. This session seeks contributions
from geochemistry, mineral physics, seismology and geodynamics
focusing on the thermal and dynamical state of the slab-wedge environment.
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GI2.01 Cabled Sea Floor
Observatories (co-sponsored by OS)
This session seeks contributions to produce further
practical plans for long term monitoring
of ocean environments with capability in geophysics, geotechnics,
chemistry,
biochemistry oceanography, biology and fisheries. Our goal is to
bring researchers, technicians,
engineers and educators from both industry and academia together
in an multidisciplinary session
to discuss, stimulate and coordinate this development of interactive
observatory based research and education. The absolute deadline for
abstract receipt
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HS11 Geomorphic processes
on multiple scales
The links between tectonics and climate
are forged by geomorphic processes and expressed in Earth's topography.
This session will explore links between Earth surface process and
form across a range of spatial and temporal scales, from hillslope
failure to orogenesis. We welcome contributions on large-scale
relationships between tectonic, climatic, and geomorphic processes,
associated particulate and dissolved fluxes and resulting landscape
evolution and geologic record, but also detailed observations and
analyses of geomorphic processes and their interactions. Contributions
should be motivated by quantitative analyses and field observations
of a geomorophological, geochemical and/or geophysical nature,
and may pertain to subaerial or subaqueous settings, and tectonically
active and ancient terrains alike.
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OS21 Ocean margin hydrogeology
Advective transport of solutes and heat
by fluids beneath the seafloor significantly contribute to global
mass budgets and cooling of the lithosphere. In areas of rapid
loading and low permeability, high pore pressures affect continental
slope stability, fault strength, and drive mud volcanism at both
active and passive margins. Furthermore, fluid flow has a direct
impact on gas hydrate reservoirs. The purpose of this session is
to highlight research issues in subseafloor hydrology and foster
interdisciplinary collaborations. Contributions from geophysicists,
hydrologists, geochemists, geologists and engineers are welcome.
Possible topics include simulation of subseafloor flow including coupled
hydrothermal or hydromechanical models, seafloor hydrologic instrumentation,
observations used to infer flow and pore pressure, and studies of effects
of subsurface flow on geological processes.
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SM12 Physics and Mechanics of Earthquakes and Faulting
This session focuses on fundamental physical and mechanical
processes involved during earthquakes and faulting. Papers on all
aspects of
non linear processes related to fault mechanics are welcome, including
simulations and observations of fault growth process; fault heterogeneities
characterization (geometry, displacement and stress fields), development
and feedback on the fracture process; rupture dynamics; frictional
behavior of complex interfaces; modeling of earthquake rupture
through analytical, numerical and analogical methods. Scaling from
laboratory
results to field observation will also be emphasized.
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TS2.03 The Central and
South American Trench System
The study of the Central and South American
Trench systems led to powerful data sets, which allow a continuous
investigation of the subduction regimes from Nicaragua to southern
Chile. A large variety of subduction related processes are observed
along this margin. Erosion and accretion are currently effective
along different settings along the trench, offsets in volcanic
chains mark changes in the tectonic geometry, seamounts and ridges
imprint their scarps onto the slope. Material flux within this
scenario results in widespread distribution of gas hydrates, carbonate
crust and mud volcanoes. We like to encourage submission of abstracts
covering this large variety of events. This session will offer
the possibility for a comprehensive description and comparison
of the margin provinces and their related tectonics.
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TS2.06 Uplift, mountain
building, denudation, and climate
This session aims to focus on the interaction
between topography, tectonics, surface processes and climate over
all time and spatial scales. In particular, we are concerned with
the interaction between the processes of denudation and tectonics
and between uplift-enhanced erosion, chemical weathering and long-term
climate change. The session will include both studies on active
systems and on the past records in sediments and in the oceans.
Relevant topics include:-
- The absolute and relative rates of
surface processes (e.g physical erosion and chemical weathering,
mass and chemical transport) and what controls those rates.
- Interaction between the processes
of denudation and tectonics. In particular do changes in erosion
rates due to changes in climate affect tectonics?
- Evidence for (or against) long term
changes in climate related to mountain building.
This session aims to summarise the current
state of research in this area and promote discussion on the outstanding
issues and future research directions (such as technical and analytical
developments and the robust integration of modelling and observations).
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TS3.03 Conjugate Rifted
Continental Margins
Conjugate continental margin pairs are
formed by extension and subsequent breakup of single segments of
continental lithosphere. It has long been recognized that to more
fully understand this process requires theoretical and observational
analyses of the complete conjugate system. A number of recent studies
have been specifically designed to look at conjugate margin pairs
and offer opportunities for new advances in the analysis of continental
breakup. In parallel with these experimental approaches, increased
computational resources are allowing more realistic modelling of
the breakup process including the coupled effects of faulting,
ductile flow and magmatism. The purpose of this symposium is to
assist these advances by soliciting contributions from research
groups involved in either observational or theoretical studies
of conjugate rifted margin segments, with the goal of stimulating
debate on such issues as margin (a)symmetry, lithospheric simple
shear, and the role of synrift magmatism. This session is complementary
to session T3.04 (Continental breakup above mantle plumes).
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TS4.03 Dynamics of plate
boundary fault systems from geological and geodetic data
Theories of earth deformation primarily
are built on knowledge of the relative motion of crustal blocks
at time scales ranging from a second to millions of years. No single
instrument can measure crustal deformation over all of these time-scales,
unless the results from several methods are combined. These methods
typically include, but are not limited to geological field studies,
geo- and thermochronology, geodesy, paleogeodesy, paleoseismology,
and geophysics. This session will focus on progress in interdisciplinary
studies of crustal deformation with special consideration to time
scale and processes. We encourage presentations that bear on plate
boundary dynamics from a variety of temporal scales and active
tectonic regions.
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TS4.07 Plate flexure and
mechanics of the lithosphere
Plate flexure is a phenomena that describes
the way planetary lithospheres respond to geological loads. By comparing
observations of flexure in the vicinity of ice sheet, volcanoe, sediment
and
orogenic loads to predictions based on elastic plate models, it has
been
possible to determine the integrated flexural rigidity of the lithosphere
and
its relationship to plate and load age. The aim of this session is
to bring
together observations (in particular gravity, topography, and seismicity
data) and models at a wide range of temporal and spatial load scales
in
order to better understand plate flexure, the mechanical behaviour
of the
lithosphere, and its geodynamical consequences. Contributions that
address
current controversies such as the relationship between effective
elastic and
seismogenic layer thickness, the rheology of continental lithosphere,
the role
that flexure plays in controlling sedimentary basin and landscape
evolution,
and the origin of the long-wavelength gravity and topography fields
of the
Earth and planets are particulary encouraged.
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TS4.10 In-situ studies
of seismogenic zones: from survey and monitoring to drilling
Several projects are moving toward drilling
seismogenic zones in a variety of tectonic regimes (subduction,
transform, rift). Common scientific objectives are to understand
the transition from aseismic to seismic slip, the physical and
chemical process controlling earthquake nucleation, propagation
and arrest, and the causes of fault weakness. One general question
is how physical properties, mineralogy, fluid chemistry, and stress
state (including fluid pressure) within the fault zone and the
surrounding rock might control the behavior of a fault zone. Multidisciplinary
studies in areas targeted for deep drilling and drilling into rupture
zones at relatively shallow depths are already changing our understanding
of earthquake rupture and the physics of faulting. The purpose
of this session is to present methods used and lessons learned
from these various in-situ fault zone studies. We welcome studies
using techniques from all disciplines, including surficial geology,
potential-field geophysics, drilling and downhole measurements,
laboratory studies on fault zone rocks and fluids, seismology,
and geodesy.
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TS5.06 Mantle exhumation
at the transition from rifting to seafloor spreading
In the last fifteen years, integrated,
multidisciplinary studies provided new insights into the processes
associated with the exhumation of subcontinental mantle at the
transition from rifting to seafloor spreading within ocean-continent-transition
zones of magma-poor rifted margins. On the other hand, mantle exhumation
is increasingly recognized as an important process along (ultra)
slow spreading ridges. In our session, we would like to address
questions such as: how do magmatic and tectonic processes interact
during the exhumation of mantle rocks? What is the genesis of the
exhumed (fertile) mantle rocks? Does melt migration trigger the
localisation of high-temperature deformation in the mantle? What
is the importance of serpentinization and fluid circulation in
the localization of low-temperature deformation? Since mantle exhumation
is a major process in extensional settings, presentations discussing
the architecture and kinematic evolution of ocean-continent-transition
zones as well as the depositional history of sediments overlying
exhumed mantle rocks are also welcome. The proposed session intends
to bring together scientists working on-land and at sea and in
margins and on mid-ocean ridges to discuss new observations, analytical
and modelling results which help to better understand and quantify
the exhumation of mantle rocks and related processes in ocean-continent
transitions.
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TS6.01 Active tectonics of
Marmara Sea and Corinth
Very active tectonics affect the Northeast
Mediterranean and adjacent regions. Westward extrusion of the
Anatolian plate along the dextral
North Anatolian Fault and subduction of the African plate along
the Hellenic Trench has led to the formation of the Marmara Sea
and North
Aegean Trough and to the development of grabens of various sizes
and orientations (e.g., Evvia and Corinth gulfs). In the aftermath
of the 1999 earthquakes in northwest Turkey, the general consensus
has been that the floor of the Marmara Sea became a target for
the next big earthquake of the North Anatolian Fault system. Activity
on the Aigion Fault system in central Greece is also of concern
for
the Gulf of Corinth region. Over the past few years, a wealth of
national and international marine and land surveys have been realized
and extensive data sets have been collected in both areas. The
main objective of this session is to continue to bring together
the scientists
that are involved in these investigations and to evaluate the various
results in a broad tectonic framework. The outcome of this session
should contribute to a better assessment of the seismic hazards
in the Marmara Sea and Corinth Gulf regions.
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TS6.05 Gondwana Breakup
and modern analogs: from the S. Atlantic to the Red Sea
The aim of this session is to review
recent results and discuss ongoing problems related to the breakup
of Gondwana and development of different passive margin types encountered
between the southern Atlantic region and the Red Sea.The aim of
this session is to review recent results and discuss ongoing problems
related to the various stages in the breakup of Gondwana and the
development of a wide variety of passive margin types such as those
encountered in the southern Atlantic region. The Red Sea is an
analog for the early stages of breakup and continental separation
and the session therefore gives the opportunity for exchange of
observations and ideas between the active and the fossil systems.
We intend this session to integrate
marine and terrestrial studies and we invite contributions from
all disciplines. Some of the aspects we wish to address include:
the processes and controls of initial breakup, the timing and sequence
of continental separation, the role of reactivation of older structures,
the importance of transcurrent faulting, mantle plumes and the
interplay of tectonic vs. Magmatic processes, the controls on crustal
architecture of different passive margin types and finally, the
post-breakup exhumation/subsidence history.
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VGP1.02 Magma generation
and evolution in the Earth and other terrestrial planets - a
21st Century perspective - a symposium to celebrate the 70th
birthday of Mike O'Hara
The 20th century was eventful in all
areas of Earth Science. Continental drift and sea-floor spreading
became embodied in the theory of plate tectonics, isotopically
heterogeneous mantle was identified as a byproduct of plate tectonics,
large igneous provinces were identified as possibly originating
from mantle plumes, and the list goes on. One thing these revolutions
have in common is the process of scientific debate. The field of
igneous petrology and geochemistry has had its share of creativity
and debate. These include the identification, nature and composition
of primary magmas, the physics and chemistry of the melting process,
the physical and chemical consequences of magma chamber processes,
phase equilibria, the thermodynamics of melting, and trace element
behaviors in response to magma generation and evolution. These
are scientific problems that Mike O’Hara has examined for
igneous rocks on Earth and the Earth’s moon for the last
half century. Part of this body of work is now acknowledged as
fundamental truths in igneous petrology, and some is considered
conjectural. All would agree that he has stimulated scientific
debate on a wide range of issues, and that modern igneous petrology
would not be the same without him. The year 2003 is the 70th birthday
of Mike O’Hara, and it also marks the 35th anniversary of
two of Mike’s classic papers: [1] “The bearing of phase
equilibria studies in synthetic and natural systems on the origin
of basic and ultrabasic rocks” (Earth Science Reviews 4,
69-133, 1968); [2] “Are ocean floor basalts primary magmas?” (Nature,
220, 683-686, 1968). The first EGS-AGU-EUG Joint Assembly in Nice,
France, April 2003 presents us with an opportunity to celebrate
the 70th birthday of Mike O’Hara through a symposium in honour
of his tremendous contributions to modern igneous petrology We
propose that this symposium bring together scientists from all
parts of the world to discuss their new research on magma petrogenesis
in the Earth and other terrestrial planets. Topics include observations,
experimental petrology, igneous geochemistry, and theoretical modeling.
We emphasize the effective use of petrology and igneous geochemistry
as a means to understanding the working of the Earth and other
terrestrial planets in the 21st Century.
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VGP1.04 Extraction of
melts from the mantle, petrological and geophysical constraints
In the recent years, there have been
considerable advances in petrological models of melt movement,
experimental constraints on the rheology of melt extraction, U-series
measurements pertaining to rates of melting and porosity of melt
segregation and geophysical observations of melt distribution in
the mantle. Despite increasing sophistication, some major questions
remain unresolved. For example, how can the <1% porosities and
high melt velocities (tens of m/a) inferred from U-series analyses
be reconciled with seismic images of the melting region and experimental
constraints on mantle permeability? Uncertainty is greatly increased
when expanding models beyond one dimension. How well are melts
focussed in a channelised regime? What is the significance of off-ridge
eruptions? How does melt extraction vary over time? In this session,
we would like to bring together scientists interested in the processes
of melt extraction who have used different approaches to tackle
this question. This includes geophysical, geochemical and petrological
observations, laboratory experiments and numerical modelling. We
would like this session to cross fertilize the various fields of
investigation and to focus on key outstanding issues in the process
of melt extraction from the mantle.
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